This invention relates to a liquid fuel cell and, in particular, to a die-cut wick for use in a liquid fuel cell.
A die-cut wick for use in a liquid fuel cell is described in U.S. Pat. No. 4,611,986. The wick includes two symmetrical half-sections that can be folded in face-to-face alignment along a vertical center line. Each half-section further includes a lower body segment that has a horizontal top edge and a narrower upper tab segment centered upon the top edge of the body segment.
In assembly, the tabs are folded together and passed upwardly through the stem of a burner situated in the lid of a liquid fuel cell. The tabs are extended until the top edges of the body segments are arrested by the inside surface of the lid. The body segments are fanned out and glued to the inside of the lid to fix the tabs at a desired height above the lid. The body segments pass downwardly into the cell card carry fuel stored therein to the tabs by capillary action. In operation, the tabs are lighted and the amount of heat produced by the burner is controlled by adjusting the relative positions of the two tabs by folding them toward or away from each other.
The folded wick arrangement has worked well in practice and has shown itself to be a simple approach to controlling the flame, thus the heat output of a liquid fuel cell. The amount of control afforded by the fixed height tab, however, is limited. Gluing the body of the wick to the underside of the lid is not totally satisfactory in that the bond can be broken enabling the wick to be repositioned in the cell. The tabs of the wick will, under certain conditions, become over-saturated with fuel causing the lid of the cell to be wetted with fuel. The problem of over-saturation of a wick-equipped, disposable liquid fuel cell is addressed in U.S. Pat. No. 4,526,530. As disclosed in this patent, the stem of the burner is surrounded by a circular trough in which excess fuel is collected The trough has one or more ports that open into the fuel cell container to permit the excess fuel collected in the trough to drain back into the cell. The burner utilized in this fuel cell is rather complex and relatively expensive to manufacture thus raising the cost of the disposable cell.